High-Q resonant sensors enable ultra-sensitive force and field detection. In this talk I will describe three applications of these sensors in searches for new physics. First I will discuss our experiment which uses laser-cooled optically trapped silica microspheres to search for violations of the gravitational inverse square law at micron distances . I will explain how similar sensors could be used for gravitational wave detection at high frequencies . Finally I will describe a new method for detecting short-range spin-dependent forces from axion-like particles based on nuclear magnetic resonance in hyperpolarized Helium-3. The method can potentially improve previous experimental bounds by several orders of magnitude and can probe deep into the theoretically interesting regime for the QCD axion .  A.Geraci, S. Papp, and J. Kitching, Phys. Rev. Lett. 105, 101101 (2010),  A. Arvanitaki and A. Geraci, Phys. Rev. Lett. 110, 071105 (2013),  A. Arvanitaki and A. Geraci, arxiv: 1403.1290 (2014).